Preliminary clinical study of outpatient anterior cervical discectomy and fusion in Chinese Han patients: a retrospective analysis
Article information
Abstract
Study Design
A retrospective analysis.
Purpose
To investigate the safety, clinical efficacy, and health economic benefits of anterior cervical discectomy and fusion (ACDF) among Chinese Han patients in an outpatient setting.
Overview of Literature
For years, ACDF has been conducted in an outpatient setting in Western countries. However, studies addressing whether this type of surgery carries the same level of safety and clinical efficacy for Chinese Han patients are scarce.
Methods
A retrospective analysis was conducted based on the clinical data of Han patients who underwent ACDF between January 2022 and May 2024. A total of 84 patients were included, and 1:1 propensity score matching was employed between 42 patients who underwent outpatient ACDF and 42 who underwent inpatient ACDF before evaluating the safety and clinical efficacy.
Results
The mean follow-up period was 3.9 months (range, 1–12 months). The fibrinogen and activated partial thromboplastin time of the outpatient and inpatient groups were comparable, which were different from the data of Caucasians in the literature. No significant differences in adverse events within 30 days following the surgery were found between the outpatient (28.6%) and inpatient (33.3%) groups. No significant differences in the Japanese Orthopaedic Association score and Neck Disability Index were noted between the two groups 1 month before and after the surgery. The readmission rates were low in the outpatient group 30 days after surgery (2.4%).
Conclusions
Consistent with the Caucasian and Black, one- to two-level ACDF conducted on Chinese Han patients in an outpatient setting demonstrated comparable safety and clinical effectiveness to routine inpatient settings.
Introduction
Cervical spondylosis is a chronic degenerative condition of the spine that affects the vertebral bodies and intervertebral discs. It can lead to disc herniation, osteophyte formation, and ligament hypertrophy, ultimately resulting in nerve root and spinal cord compression [1]. A long-term follow-up study indicated that anterior cervical discectomy and fusion (ACDF) can yield favorable outcomes when conservative treatment is ineffective [2]. It is characterized by minimal trauma, low complication rates, high fusion rates, and mild postoperative pain and demonstrated clinical effectiveness, leading to its widespread clinical application [3]. Accordingly, since 1996, ACDF has evolved into a standard outpatient procedure in Western countries [4–7].
Recent meta-analyses have shown that outpatient ACDF surgery is safe, with complication rates comparable with those of inpatient ACDF surgery in carefully selected patients [8]. A study indicated that surgeons can safely perform outpatient ACDF surgeries by using appropriate patient selection criteria and perioperative management protocols [7]. Nevertheless, it remains a high-risk operation that requires exceptional surgical skills and experience. Despite the rarity of postoperative hematoma, it is a serious complication that can lead to airway obstruction, respiratory difficulties, and spinal cord compression, and in severe cases, it may be life-threatening [9]. Although evidence suggests that a postoperative observation period of 4–6 hours following outpatient ACDF for 1–2 levels is safe and feasible, significant complications, such as hematoma, can typically be identified within this timeframe [5,6]. Reports on outpatient ACDF surgeries in Western countries primarily focus on Caucasians [10]. The coagulation function varies across different racial groups [11]. Specifically, East Asians tend to have a higher bleeding risk than Caucasians [12,13], which may contribute to the high risk of postoperative hematoma in East Asians undergoing ACDF. Consequently, probably due to concerns about the risk of death [14], there have been no reports in East Asia so far.
Currently, orthopedic outpatient surgeries, such as arthroscopy, vertebroplasty, and percutaneous endoscopic lumbar discectomy, are conducted in China [15–17]. However, outpatient ACDF surgery is currently in its preliminary exploration stage. With the increasing experience of surgeons using microscopes/loupes, as well as advancements in implants, ACDF has evolved into a common procedure [18]. In recent years, based on our advanced ACDF surgical techniques, strict patient inclusion criteria, and precise postoperative management, our department has initially explored outpatient ACDF surgery among Chinese Han patients. Thus, this study retrospectively analyzed and reported the safety, efficacy, adverse events, etc., associated with the technique.
Materials and Methods
All methods performed in this retrospective study were conducted in accordance with the Declaration of Helsinki, and this study was approved by the Medical Ethics Committee of the Second Affiliated Hospital of Soochow University (approval no., JD-HG-2022-47). The participants provided written informed consent.
Participants
The patients had to meet all of the inclusion and exclusion criteria (Table 1). A total of 84 patients who underwent ACDF surgery at our hospital between January 2022 and May 2024 were enrolled. Among them, 1:1 propensity score matching was employed between 42 patients who underwent outpatient ACDF (outpatient group) and 42 who underwent inpatient ACDF (inpatient group) in the same period based on body mass index (BMI), diagnoses, and surgical levels. All procedures were performed by the same medical team, and the outpatient group had to meet all outpatient surgery discharge criteria.
Baseline characteristics of patient groups
Inclusion and exclusion criteria
The inclusion criteria were as follows: (1) diagnosis of radiculopathy and cervical myelopathy based on clinical symptoms, signs, and imaging; (2) failure of conventional conservative treatment; (3) age <65 years or ≥65 years without serious medical diseases; (4) BMI of 18.5–40.0 kg/m2; (5) American Society of Anesthesiologists grade ≤II; (6) surgical segment between C3/4 and C6/7 and surgical levels of ≤3; (7) presence of diabetes: fasting blood glucose <10 mmol/L, random blood glucose <12 mmol/L; (8) presence of hypertension: blood pressure <130/85 mm Hg; (9) distance of the home address of the outpatient group to the facility with emergency room is within 30-minute drive; and (10) Chinese Han ancestry. The exclusion criteria were as follows: (1) previous history of cervical spine surgery, severe cervical spinal stenosis, traumatic causes, and severe osteoporosis; (2) infections, malignant tumors, active hepatitis, thrombosis, and acute cerebral infarction; (3) cardiovascular disease: New York Heart Association grades 3–4, congestive heart failure, and myocardial infarction within 6 months; (4) chronic obstructive pulmonary disease; (5) chronic or end-stage renal disease; (6) coagulation dysfunction or intake of anticoagulant drugs; (7) anemia; (8) long-term use of opioids; and (9) presence of mental illnesses such as severe anxiety or mood disorders.
Surgical technique
An anterior approach to the cervical spine is performed by cervicectomy, and the surgeons proceed to remove the nucleus pulposus tissue, scrape the cartilage of the endplates, and remove the hyperplastic osteophytes. The nerves and spinal cord are adequately decompressed with the assistance of a microscope/loupes. The disc space is filled with a cage prefilled mainly with autologous bone (such as hyperplastic osteophytes). Drains are placed in each patient. The drain placed intraoperatively is removed when the postoperative output is minimal. Careful hemostasis is performed using fine bipolar electrocautery, bone wax, and hemostatic matrices occasionally.
Postoperative monitoring protocols
All patients in the outpatient group were observed in the postanesthesia care unit (PACU) for 0.5–1 hour for neck swelling and neurological status and then monitored in the ambulatory ward (equipped with ACDF-related emergency rescue equipment) until discharge. Before discharge, each patient underwent a predischarge evaluation by the surgeons. Indications for transfer to hospital care included persistent pain, hematoma, cerebrospinal fluid leak, or any perioperative complications requiring inpatient management. All patients and their families receive a 24-hour active phone number to contact if they have any concerns after discharge.
Outpatient surgery discharge criteria
The discharge criteria were as follows: (1) stable vital signs, (2) good mental state and appetite, (3) absence of severe dysphagia, (4) relatively stable gait without dizziness, (5) nausea and vomiting unrelated to treatment; (6) Visual Analog Scale (VAS) score ≤3, and (7) a normal wound appearance without obvious neck swelling.
Outpatient surgery postdischarge management
The outpatient surgery team conducted a follow-up call within 24 hours after discharge. The postdischarge management mainly included the following (1) rehabilitation exercises; (2) wound care, with regular dressing changes; (3) guidance on medication usage and postoperative follow-up; and (4) informing the patient and their family that they should immediately contact the outpatient surgery team by phone for urgent assistance if clinical symptoms such as prevertebral soft tissue swelling and severe dysphagia occur, and the further treatment options will be determined after the doctor’s evaluation.
Outcome assessments
The variables collected from the two groups included baseline characteristics, preoperative waiting time, length of hospital stay, postoperative adverse events, readmission rates, hospital costs (excluding the cost of intraoperative implant materials), drain output, estimated blood loss (EBL), operative duration, length of stay in the PACU, hematologic labs, and VAS score 1 day after surgery. In addition, functional scores were recorded before and 1 month after surgery, clinical efficacy was evaluated using the modified MacNab criteria, and the overall satisfaction with the care provided (subjective score from 0 to 10) was evaluated before discharge.
Statistical analysis
Statistical analyses were conducted using IBM SPSS Statistics ver. 25.0 (IBM Corp., Armonk, NY, USA). To reduce baseline differences between the cohorts, propensity scores were used to match inpatient and outpatient ACDFs. The independent sample t-test was used to assess differences in the mean values of continuous variables such as age, BMI, time, costs, hematologic labs, drain output, and functional score parameters. Preoperative and postoperative functional scores and hematologic labs were compared using paired t-test. Sex, preoperative comorbidities (pre/no), disease classification (radiculopathy or myelopathy), number of surgical levels (1, 2, or 3), incidence of postoperative adverse events, readmission rates, excellent rate of clinical efficacy evaluation by the modified MacNab criteria, and patient satisfaction count data were expressed as frequency. The chi-square test or Fisher’s exact probability method was used for comparison of counting data between the two groups. A p-value of <0.05 was considered significant.
Results
Outcomes
No significant difference in baseline data was found between the two groups (p>0.05) (Table 1). No significant variations in fibrinogen, activated partial thromboplastin time (APTT), EBL, drain outputs, and operative duration were noted between the two groups (p>0.05) (Table 2). Meanwhile, postoperative hemoglobin (Hb) and hematocrit (Hct) levels decreased to varying degrees in both groups (p<0.05) (Tables 3, 4). In comparison with the inpatient group, the outpatient group has significantly shortened preoperative waiting time and length of hospital stay and significantly reduced hospital costs (p<0.05) (Table 2). However, a significant difference in patient satisfaction was noted between the two groups, with a relatively high satisfaction rate in the outpatient group. All patients in the outpatient group were discharged home.
Comparison of outcome indicators between the two groups
Differences in preoperative versus postoperative hemoglobin of two groups
Differences in preoperative versus postoperative hematocrit of two groups
Surgical results
No serious adverse events such as hematoma, cerebrospinal fluid leakage, spinal cord or nerve injury, surgical site infection, or death were recorded in either cohort. Among the minor adverse events occurring within 30 days postoperatively, the outpatient group experienced eight cases of mild dysphagia, two of nausea and vomiting, one of dizziness, and one of fever. In the inpatient group, nine cases of mild dysphagia, three of nausea and vomiting, and two of pain were recorded. No significant difference in the incidence of complications was found between the two groups within 30 days postoperatively (p>0.05) (Table 5). In the two groups, no unplanned reoperations occurred 30 days after surgery. However, one case (2.4%) of unplanned readmission within 30 days after surgery was noted in the outpatient group. Nevertheless, no significant difference was noted between the two groups (p>0.05) (Table 5).
30 Days post-operation adverse events data of patient groups
Management of postoperative adverse events
Dysphagia was the primary postoperative complication observed in both cohorts. Most dysphagia cases were mild and resolved after steroid injections. The outpatient group experienced two cases of nausea and vomiting, whereas the inpatient group had three cases, and their symptoms improved following metoclopramide injections. The outpatient group reported one case of dizziness, which was considered to be related to opioid analgesics, and the symptoms improved after switching to nonsteroidal anti-inflammatory drugs. In addition, one case of fever was recorded in the outpatient group, with lab tests indicating high white blood cell counts and procalcitonin levels. After 1 week of treatment with appropriate antibiotics, the patient’s temperature returned to normal, and follow-up tests showed normal white blood cell counts and procalcitonin levels. The inpatient group reported two cases of postoperative pain, which were alleviated after nerve root blocks.
Clinical results
The VAS scores on postoperative day 1 were lower than those in the inpatient group (p<0.001) (Table 2). The Japanese Orthopaedic Association (JOA) scores and Neck Disability Index in the two groups were significantly improved 1 month postoperatively (p<0.001) (Tables 6, 7). Both cohorts experienced significant improvements in clinical scores compared with their preoperative values. According to the modified MacNab criteria, in the outpatient group, 39 cases were excellent, two were good, one was fine, and 0 were bad. In the inpatient group, 38 cases were excellent, two were good, two were fine, and 0 were bad. The difference between the two groups was not significant (Table 8).
JOA score before and 1 month after surgery of two groups
NDI before and 1 month after surgery of two groups
Modified Macnab criteria 1 month after surgery of two groups
Discussion
Outpatient ACDF surgery has rapidly improved in Europe and the United States in the past 30 years. Many studies have shown that ACDF performed as an outpatient surgery has lower complication and readmission rates, with the same level of safety as inpatient surgery [4,8,19]. However, compared with the Black and Caucasians, the coagulation functions of the East Asians were significantly different [11,20]. As one of the largest racial groups in East Asia, the Chinese might experience more bleeding, which usually requires careful hemostasis intraoperatively [12,13], and the risk of postoperative hematoma may be higher. Thus, whether the safety of ACDF outpatient surgery in Han Chinese patients is consistent with those of the Black and Caucasians remains unaddressed. To our knowledge, this is the first study of Chinese Han patients undergoing this procedure. The results showed no significant difference in safety and efficacy between the two groups. Hospital costs, length of preoperative waiting time, and the length of hospital stay were considerably decreased in the outpatient group.
A concerning factor related to outpatient ACDF surgery was the potential inability to promptly detect postdischarge hematoma. Studies have revealed that postoperative hematoma, which is often found within 4–6 hours after surgery, is the most serious complication [5,6]. Furthermore, delayed occurrence of cervical hematoma is a rare but known complication of this surgery. O’Neill et al. [21] reported a 0.7% hematoma rate, of which 35% had a late onset. The increase in fibrinolytic activity may lead to an increase in blood loss in spine surgery [22]. Compared with the Black and Caucasian populations, the coagulation functions of the East Asian population were significantly different, with lower levels of antihaemophilia factor (factor VIII) and fibrinogen [20], in addition to a relatively prolonged APTT and decreased thrombin generation [11]. The APTT of East Asians (29.7 seconds) was significantly higher than that of Caucasians (26.4 seconds) [11]. In addition, East Asians exhibited a higher bleeding risk than Caucasians [12,13]. Therefore, East Asians may encounter increased bleeding and delayed clotting during surgery.
The mean APTT of the patients in our cohort was 33.51 seconds, which was significantly higher than previous reports of both the Black and Caucasians (26.4 seconds) [11]. No significant differences in the drain outputs and EBL were found between the outpatient group (12.21±8.22 mL and 7.26±3.72 mL, respectively) and the inpatient group (12.48±8.33 mL and 9.14±7.65 mL, respectively). Postoperative Hb and Hct levels decreased to varying degrees in both groups. The average Hb level fell by 8.43 g/L in the outpatient group and 9.02 g/L in the inpatient group, showing no significant difference between the two groups. Changes between preoperative and postoperative Hb and Hct levels include hidden blood loss and intraoperative blood loss. The levels of Hb reduction preoperatively and postoperatively in this study were lower than previously reported (10.0 g/L) [22]. This may be related to meticulous technical exposure with careful hemostasis. The international normalized ratio (INR) is a measure of the extrinsic pathway of coagulation. Previous studies have indicated that a preoperative INR value of >1.2 and preoperative anemia were high-risk factors for hematoma after ACDF [14]. The preoperative INR value of the patients was low in this study. Anemia was not noted in either group before surgery, indicating that both groups had a favorable preoperative nutritional status. This also establishes the groundwork for the expedited recovery of patients postoperatively and the safety of outpatient surgery. No epidural or retropharyngeal hematomas were found in this study. Compared with Caucasians, Chinese Han have significantly different coagulation functions, which may lead to a higher risk of intraoperative bleeding or postoperative hematoma [12,13]. However, the risk of return to the operating room is generally the same for Caucasians and Asians [23], with the most common reason being postoperative hematoma [24]. No differences were noted in the incidence of postoperative hematoma between the outpatient and inpatient groups. In general, outpatient ACDF surgery is also safe among Chinese Han patients.
In a retrospective analysis conducted by Garringer and Sasso [25], the readmission rate of outpatient ACDF surgery was 6% because of nausea and pain at the iliac bone graft site. In another study of 629 patients who underwent outpatient surgery for one-level ACDF and 365 patients who underwent outpatient surgery for two-level ACDF, Adamson et al. [5] found a delayed discharge rate of 0.8% and a readmission rate of 2.2% within 30 days. In this investigation, three patients in the outpatient group had delayed discharge because of postoperative nausea and vomiting, dysphagia, and dizziness, resulting in a delayed discharge rate of 7.1%. In addition, one patient had an unplanned readmission because of fever and dizziness on postoperative day 4, leading to an unplanned readmission rate of 2.4%. The higher delayed discharge rate in this study can be attributed to these cases being performed early in our practice and to the limited case volume.
In 1996, Silvers et al. [4] conducted a comparative analysis of 53 inpatient and 50 outpatient procedures, revealing no significant difference in complication rates. According to Gennari et al. [26], the complication rate was exceedingly low, even lower than that of patients treated as inpatients in comparative studies. Consistent with research conducted in Western countries [4,26], no significant difference in the incidence of adverse events 30 days after surgery was noted between the two cohorts in this study. Dysphagia was the primary postoperative complication observed in both cohorts, which resolved spontaneously within 3–5 days. Studies have indicated that dysphagia is a prevalent complication of ACDF. The majority of dysphagia symptoms occur in the immediate postoperative period and are typically mild, gradually diminishing over time [27]. Dysphagia significantly affects the daily life of patients who underwent outpatient ACDF. Care must focus on dysphagia prevention [27].
Postoperative nausea and vomiting are among the main factors contributing to extended hospital stay for outpatient surgery, and such postdischarge complications may also lead to unplanned readmission [28]. Consequently, a risk assessment for postoperative nausea and vomiting must be undertaken in patients undergoing outpatient ACDF, and multimodal prophylaxis must be implemented based on the risk assessment levels [28]. Postoperative dizziness hinders patients from promptly engaging in ground-based exercise for rehabilitation, thus significantly impeding postoperative recovery. The primary factors comprise a history of motion sickness, postoperative nausea and vomiting, residual effects of general anesthetic drugs, and perioperative use of tramadol and pregabalin [29].
With the introduction of the concept of enhanced recovery after surgery, the evaluation of the clinical efficacy is not only limited to the surgical complication and readmission rates but also to subjective outcome indicators. Patel et al. [19] conducted a retrospective analysis of 100 outpatient and 172 inpatient surgery cases. They compared the NDI and VAS scores of the two groups before the operation and found no significant difference in the NDI and VAS scores at each time point between the two groups. They found no significant difference in the clinical efficacy between the two groups [19]. Consistent with the results of Patel et al. [19], the present study did not find a significant difference in the JOA score and NDI between the two groups at each time point. In addition, no significant difference in the excellent rate in the MacNab criteria clinical efficacy evaluation was noted between the two groups, and the symptoms of cervical spondylosis in the two groups were significantly improved. In this study, the VAS scores of the two groups were evaluated on postoperative day 1, and the outpatient group had ≤3 points, indicating that all patients met the discharge criteria for pain. The VAS score of the outpatient group was significantly lower than that of the inpatient group for the following reasons: (1) it may be related to adequate postoperative analgesia in the outpatient group and (2) to the incomplete remission of radicular symptoms after surgery in two inpatients.
Considering healthcare cost reduction, shortening the length of hospital stays and decreasing perioperative morbidity are among the means to reduce expenses. In inpatient ACDF in China, preoperative examinations will be completed in 1–2 days, and postoperative monitoring and care will be provided in the hospital for 3–5 days following the surgery. In addition, Silvers et al. [4] demonstrated that outpatient ACDF reduced an average of $1,800 per patient. This study found that one- and two-level outpatient surgeries can reduce approximately RMB 5,000 and 2,500 Yuan in hospital costs, respectively, leading to substantial cost savings and a positive economic effect. Erikson et al. [30] examined 58 outpatient ACDFs and found high satisfaction and no compromise of patient safety. The present study showed similar results. The overall satisfaction rate was 9.81/10 in the outpatient group, which was significantly higher than that in the inpatient group.
This study has several limitations. First, the findings are confined to healthy persons and may not be generalizable to populations with significant comorbidities. Second, this was a retrospective study, which may have some bias in case selection. Third, the sample size of the patients included was small, consisting entirely of early-stage outpatient ACDF surgical cases with a relatively short follow-up period. Although no life-threatening complications (such as postoperative hematoma) occurred, the possibility of other rare or serious complications in larger sample studies cannot be excluded. Therefore, a large, prospective multicenter randomized controlled study is urgently needed to determine the efficacy and safety of outpatient ACDF surgery in China.
Conclusions
The results indicate that with proper patient selection, outpatient ACDF surgery has comparable safety and clinical efficacy to inpatient surgery among Chinese Han patients. Furthermore, among Chinese Han patients, outpatient ACDF surgery has equal safety and clinical efficacy to Black and Caucasian patients, has high patient satisfaction, and could significantly reduce hospital costs. In addition, strict access standards and discharge criteria can ensure sufficient development of outpatient ACDF surgery.
Key Points
The results revealed that with proper patient selection, outpatient anterior cervical discectomy and fusion (ACDF) surgery has equal safety and clinical efficacy to inpatient ACDF among Chinese Han patients.
Among Chinese Han patients, outpatient ACDF has equal safety and clinical efficacy to Black and Caucasian patients, has high patient satisfaction, and could significantly reduce hospital costs.
The strict access standards and discharge criteria can ensure sufficient development of ACDF outpatient surgery.
Notes
Conflict of Interest
No potential conflict of interest relevant to this article was reported.
Funding
This work was supported by the Social Development Key Programs of Jiangsu Province Advanced Clinical Technology (BE2023705), and Jiangsu Provincial Medical Key Discipline (JSDW202223).
Author Contributions
Conceptualization: X Zhou. Data curation: LL, ZC, X Zhao, MZ. Formal analysis: LL, ZC, X Zhao, MZ. Investigation: LL, ZC, X Zhao, ZZ, MZ. Methodology: LL, ZC, JD, X Zhao, ZZ, X Zhou. Validation: LL, ZC, JD, X Zhao, X Zhou. Writing-original draft: LL, ZC, JD, X Zhao. Writing-review & editing: MZ, X Zhou. Project administration: MZ, X Zhou. Supervision: X Zhou. Funding acquisition: X Zhou. Final approval of the manuscript: all authors.